scott



Jan. 31 1928.

w. M. sc'rr SWITCHING. MECHANISM 4 Sheets-Sheet l Filed April 21. 1924 Jan. 31, 1928.

W. M. SCOTT swITcHING MECHANISM 4 Sheets-Sheet 2 v Filed April 21. 1924` sBf E@ t ATTORNEY Jan. 31, 1928.

1,657,486 w. M. SCOTT swmcame MECHANISM Filed April 21, 1924 4 sheets-sheet 3 l A@ Q/ IN VEN TOR BY MM5@ ATTORNEY Jan. 31, 192s. 1,657,486

W. M. SCOTT SWITCHING MECHANISM Filed April 21, 1924 4 25ms-Sheet 4 l ATTORNEY Vengages and operates the latch ly in Figs. l() and 11, having the hole 17 for passage `of the stud 13 and havingthe stud 18 entering a hole in the. base 1 and provided with the spacer' member 19.

'The movable contact member 11 is carrier by a-n arm 20, pivoted at 21 and operated b y the toggle con'iprising the links'22 and 23, p'ivoted to eac-h other at 24, and the link pivoted at 25 to a bracket or housing carried by the` base 1, and the link 23 pivoted to the arm at 23% The toggle ior the eircuit closing Aposition indicated :is under travelled, but held extended by the latch 2h, which engages a pin or roller 2T upon the member 23 to lock the circuit breaker in circuit closingrposition. Vlfhelatch is automatically actuated by the armature 28, which is attracted upwardly toward the pole pieces 29 when the current traversing the windiiig 12 attains apr'edeterinined magnitude, the

armature 28 carrying the men'iber El() which actuator 3l, which in turn actuates the latch 26 to move it in clockwise direction to trip or tree the Vbreaker structure.

The member 23 carries the pin or arm 8L, adapted to loe-engaged and depressed bythe member D, upon operation ot' the handle C,

`=to reset the circuit breaker arm after it has Y been tripped. Motion et the member D in opposite direction, by movement ot the handle C in opposite direction, causes depression of the corresponding member 32 of the other arm B to move vit to circuit closing position forresetting it after havingl been tripped, i

The circuit breaker mechanism described is .enclosed within a housinglLot sheet metal or othersuitable material, having the hook members 33, by which it is hooked and pivot-- ed upon pins 34 carried by the rear housing I, ot sheet metal or other suitable material,

enclosing the aforesaid rear circuit breaker terminals 6 and 16 andthe rear base 35, oi' insulating material, which latter and the .housing I are secured to any suitable fixed support byv screws 36, by which the entire structure, including the base 1 and the circuit breaker mechanism, is supported.

f The-base 1 is also providedavith hook members 37, which hook -upon pins SL1- carried bythe rear housingr I, whereby the hous- "iiig lil, which carries the'resetting mechav.msm D, may be removed indepemilently and Lsecuredthereto screw separately irom the base 1, which is also removable tromjthe rear housing I.

. Aidjacentthe'lower endet' the base 1 are 38, Fig. Vl, having the Unthreaded.tapered dowel ends 38 which enter the holes 38?. Fig. 2,'in the members V38? secured to the rear housing structure -As thebase 1 swings'upon the, pivot pms ,34 .adyacent its iuppei" end, the `dowels 38?* elntertlie holes 38 and sognide the base 1 to detilnte and proper relation with respect its bottom one or more angle members iin".

Fig. 1, which engage the liront ,tace o t the base 1, forcing it to the position indicated in Fig. 1 when the housing H is swung upon the pivot pins 3l to the position indicated in Fig. 1 in which itis locked by the structure hereinafter described. 'lhe constriu-tion is such that alter the base Vl has` been hung` by its hinge hooks 37 upon the hinge pins Sli. the base will rest with `the sluliplemental rear circuit breaker terminals and lo in engage ment with their coacting tern'iinals. hereinatter described, with the dowels liti" enter-IlmA the holes 38h. The base 1 will not be in its linal or operative position indicated in Fig. 1, but its lower end lwill be somewhat to the rightot its tinal position indicated. .l'ilowever, upon moving` the housing H upon its hook hinges 323 in clockwise direction. the rear housing structure l, the base 1 and tinl housing H will be brought into tinal and proper position indicated in Fig. 1, the lugs 38 torcing the base 1 to its linal position indicated.

The housing H is held and locked in the position indicated by the toggle comprisingl the link 39, pivoted to the housing` ll at it), and the bail or link .41 pivoted at 42 to the rear housing l, the links $39 and -l-l beinfl slightly overtravelled in the position indicated, and thereby holding and lockingy the housing H.

Secured to the front ot the rear base i by screws lf'iare the upper terminals il.

shown separately in Figs. di and 5, having -the lower end wall ot the, housing l.

l livoted to each ot' the upper and lower terminals il and all), at 55, is a pair ol' links or lever arms 5G, shown selnufately in Figs. lil and 15, and carrying at their llower and forward ends ay pivot pin` 57 engaging iu the slot 58a in the rear tace of the contact member or block ils iiidicated in Figs. l2 and 13, the slot 58 has a width, vertically, substantially equal to the diameter ot' the pivot pin 5i". and has a depth nuittn'iall \v greater than its width, whereby; the block liti will suitably align itself'. '.lhe blocks 58 abut against and electrically connect with the rea-r circuit breaker terminals and 16. Electrical connection is made between the blocks 5e and their terminals lll and i9 by the flexible laminated U-shaped metal conductors 59 secured to the blocks 5d by the screws 60 and secured to the terminals is and 19 by the screws Gil. Between the heads et' the screws 50 and the connector structure 59 is a plate 62 carrying the stud G5, received. inte one end oft the helical spring (rl disposed between the plate (52 and the rear leg ol the U-shaped member 59, each spring (il: pressing forwardly and thereby pressing its associated block 5S against the associated rear circuit breaker terminal G or lo. rlhe members 59 may be springs alone pressing the contacts 58 forwardly, or assisting the springs ell in so pressing the contacts 58 forwardly. The spring Gel is so located by lug 63 with respect to a block 58 that the pressure et the spring 64. is exerted upon the rear oit the bleek 58 opposite the middle et its contact surface, the contact being completely self-aligning, and the contact pressure between a bleek 58 and its co-acting supplemental rear circuit breaker terminal is so great as to ensure high conductivity at their contact.

rlili-e 'pivots 55 and 57 ttor the Contact Vblocks 58 are so disposed with respect to the pivotal axis 34. ot the base l that in swinging the base in clockwise direction, Fig. 1, toward the rear housing structure I, the supplemental circuit breaker terminals 6 and 1G engage the blocks 58, pressing them rearwardly and at the same time wiping or rubbing upon them to etlfect high conductivity at their contacts.

llfheu 'tor any reason', as 'lior quick substitution or replacement oli one switch or circuit breaker unit or mechanism lier another, it is necessary or desirable to remove the circuit breaker or switch unit, the housingl lil is removed, by Virst rotating the toggle link 39 in cloclmvise direction, Fig. l, to position where the link il disengages from the notch in the link S9, thereby unlockingl the housing` H, which may then be swung' in counterclockwise direction and unhooked and removed from the pins Thereupon the lower end o'l the base l is ilreed, and it with the attached circuit breaker mechanism may be swung about and rotated in counterclockwise direction and unhookcd trom the pins Sli.

As the base l swings outwardly as described, the blocks 58 carried by the rear base follow the rear circuit breaker terminals 6 and 1G until the ends 5G@L on the links 56 engage the front 'liace of the rear base 35, whereupon the forward movement of the members 58 under the influence et the springs (34 is arrested. The circuit breaker carried by the base l is rennived troni the rear housing l? and sininiltaneeusly disconnected from the supply and consumption circuit conductors i8 and 5e.

ln replacing the unit, or substituting another unit, the base l is tiret hooked upon the pins llland then swung in clockwise direction, bringing the rear circuit breaker terminals G and 16 into engagement with the forwardly held contacts 58, and as the base is moved to the position indicated in ltig. l, it is guided into position by the dowel. ended screws 38, and the contact blocks 58 recede and compress the springs (ist, but maintain goed electrical contact with the rear circuit breaker terminals, this backward 'yielding ot the contacts 58 being accompanied by a clockwise rotation ot the links 5G upon their pivots 55 to the position indicated in lzlig. l, this movement beingl accompanied by a wiping or rubbing engagement el the supplemental circuit breaker terminals (l and 1G upon the contact blocks 58, and by seltaligning movements of the block 58 as perinitted by their slots 5S*1 in co-action with. the pivot pins 5T. During the above described movements ot the contact blocks 58, they are maintained in perfect electrical connection with the rear terminals elfland 4:9, and there'l'ore with the contacts i8 and 5e, by the flexible connectors 59.

By the construction described, there are accordingly provided rear terminals or centa-ct blocks lor the switch or circuit breaker unit which engage with. yielding Contact blocks carried by the rear base 35 which carries terminals to which the supply and consun'iption circuit conductors are permanently connected. llrccordingly, to remove or replace a switch or circuit brei ker unit it is not necessary to have access te or con.- nect er disconnect the supply and consumption circuit coiuluctors which heretofore have been connected directly to the switch or circuit breaker studs 3 and 3, necessitating disconnection el the supply and consumption circuit conductors :troni these studs upon ren'ioving the switch or circuit breaker unit from the rear housing or other support.

In Figs. lo et seo. there is illustrated a inodilied construction having in general, however, the saine l'irinciple oil.I operation. ln this case the yiehling contact striuzture is carried by the switch or circuit breaker base and co-acts with simple terminals carried by the second base or rear housing.

Between the nuts l; and on each stud 3, and between the nuts lll; and l5 on each stud 13, is held the bracket (S5, shown separately in Figs. 22 and 2?, on the rear ol the base l and having a. lug GG extending into the base l properly to locate the bracket and prevent it Yfrom turning. Between each. oli

the nuts 5 and l5 and the bracket 55 held ire one end ot the flexible laminated conductor 59, shown separately in Figs. 24 and 25, U-shaped Vas before, and connected at its tree end withA the Contact button or block 58 having the stem G7 slidable normally to the rear tace ot the base l in the bracket (i5-and its U-'shaped extension 68, a. spring 64 being coniined between the bracket 65 and a shoulder on the stud 67 and opposing movement ot the block 58 toward the right, as viewed inV Fig. i6. rlhe springs 64: press the blocks 58 into Vengagement with the supply andconsumption circuit terminals 4.1L and l0 secured, respectively, by screws 43 and 5() to the 'trout tace ot the rear base 85. rlhere extend through the'uppcr Aterminals ist the bolts 69, upon each ot which is threaded the mits 7() and 7l, holding the terminal to the base 35 and clampingthe supply circuit terminal el? `to the terminal A14. `Similarly, each lower terminal 419,

shown separately in FigsQO and 2l, is held by the bolt T2 and nuts 78 to the liront tace ot' the rear Vbase', the bolt and nuts serving also to clamp the terminal 53 ot a consumption circuit conductor to the terminalLlQ.

ln this modiiieation the rear switch or circuit breakeiteiininals, as 58, are yieldingly mounted and engage the Xed or unyieldingly mounted supply and consumption circuit `terminals ll and 49.

The operation is similar to that herein- Ibefore described in that the circuit breaker or switch mechanism carried by and torming a unit with they base l is removable and replaceable without need tor access ,to or connection or vdisconnection of the supply and consun'iption circuit conductors, the springs Gil, when the base l is fnvung` towards the right, Fig. 16, moving the contacts ltoward the lett until the pins 67a engage the legs .68 olf the brackets 65.. ln returning the switch or circuit breakerunit to nor-mal position, or in applyinga substitute. the ybase l is moved into the position indicated,the contacts 59. engaging the terminals lll and 49, and yielding in opposition tov thesprings G4. Here again the con-A ductors 59 maintain good electrical contact between the switch or circuit breaker studs and the contacts 58.

lt is accordingly chaincteristic ot my in- 'vention that a switch or Vcircuit breaker unit is provided. in addition to-the usual lined and movable contact n'ien'ibers ot the switch or circuit breaker, with one or more terminals or Vcontacts engaging and electrically connecting with contacts or terminals with which the supply and consumption circuit conductors areconnected, whereby the switch or circuit breaker unitis detachable or removable and replaceable as such without need tor access to or connection or disconnection of the conductors of the circuit in which the switch or circuit breaker is connected.

In accordamze with my invention, the terminals or contacts, such as fit and Ll-S), are in etlect permanently secured in place and the circuit conductors in ellcct permanently connected thereto, whereby the terminals ill; and del) are in etlect a part ol the permanent wi ringl the circuit or system.

llhat I claim is:

l. The combination with a housing'. olf tern minal structure therein connected willi the circuit conductor system. a base movable with respect to said housingn and terminal structure, switching mechanism secured upon one side ot said base, supplemental terminal structure carried by said base on the opposite side thereof from said switchingr mechanism and connected with said switching' mechanism, and means holdingsaid terminal sl ructures in engagement with each other comprising a second housingl detached from and abutting against said base, and means l'or holding said second housing' in predetermined position with respect to said housing and hist-named terminal striu-ture.

2. The combination with a housing` ot terminal structure therein connected with the circuit conductor system, a base movable with respect to said housing' and terminal structure, switch mechanism secured upon one side oi' said base.5 supplemental terminal structure carried by said base on the opposite side thereof Jfrom sai-d switchim r mechanism and connected with said switching' mecha nism, a second housing enclosingsaid switchine` mechanism and thrustingr against said base, and means holdingsaid second housine in predetermined po,^'tion with resp-ect to said lirst-named housing' and terminal .st rncturc and thereby holdingr said terminal structures in engagement with each other.

3. The combination with a housing. of terminal structure therein connected with the circuit conductor system. a base carried b v and movable with respect to said housing,

switching mechanism secured upon one side ot said base, supplemental terminal structure carried by said base on the opposite .side ther-cof from said switching mechanism and connected with said switchiin l mechanism. and means tor holding said terminal structuresin engagement with cach olhcr coml prising' a second housing; lor said swilchinnj mechanism carried by said lirst housing` and movable with respect thereto and with respect to said base, and means holding` said second housing in prcdeterniiued position with respect to said housing.

rlhe combination with a housing'. ol' terminal structure therein connected with tbe circuit conductor syst-em. a base carried by and movable with respect to said housing'. switching mechanism secured upon one side yotsaid base, supplemental terminal structure lijn ifi)

carried by Said basic on the opposite side thereot from said vitching mechanism and connected with said switching mechanism, a. second housing carried by :i nd movable with respect to said tiret-named housing and with respect to said base, and means holding` said second housing in engagement with said base and to said tiret-named housing' and thereby holding scid terminal stri:ctnrce` in engage nient with cach other.

The coinbirnltion with a switch unit comprising a base and switching mechanism carried thereby ot nupplemental terminal ntructnre` carried b v said bese and connected with eaid switching inechanisnn tcriniinil etruiiwiuro connected with the `circuit conductor system, a pivoted contact electrically connected with one ot said terminal structures and abutting againetanother ot seid terminal structures, a spring -c'il'ecting n'rovement ot said contact toward said other et said ter mina] etructurcsq and means for limiting, the movement ot said contact toward ,said other ot Said terminal etructuree.

G. ',he conibination with a ewitch unit coinrnieing a base and switching mechanism cnrried thereby oit supplemental terminal structure carried by said bose and connected with said sii/'itching mechanienn ter, v.l structure connected with the circuit conductor svatenna Contact electrically connccted with one ot said terminal structures and abutting :igainet another ot eaid terniinal. structuresL and a pivoted linh support4- ing said contact.

7. The combination with a Switch unit comprising a base and switching mechanism carried thercbv1 ot siljpnlen'iental terminal structure carried by said base and connected with eaid switching mechanism, tern'iinal Structure connected with the: circnit condnctor system, a contact elcctri allyY connected with one oit `eaid terminal etructnreeI and admitting against another ot eind terminal strurtuies, and a link pivotcd upon one ot said` terminal structuren and to Quid contact.

8. 'ilhe combination witl a switch unit comprising a base and switching mechanism carried thereby, oit' supplemental terminal structure carried b v said base and connected with said switching mechanif-im, terminal structure connected with the circuit `corductor sjvstenny a contact electrically conf nected with one ot said terminal etructiiires und abutting againet another oit ,said terminal structures, a pivoted link supporting lSaid contact7 a spring effecting movement ot said contact toward Said other ot said terminal structures, and menne on said link tor limiting :said movement ot said contact.

9. The combination with a switch unit comprising a base and Switching mechanism carried thereby on one side thereof, ot eup-` pleinental terminal structure on the opposite eide ot said base and connected with said switching' mechanism and comprising a terminal` having' a contact tace substantialljy parallel With the rear tace of said base, and terminal structure with respect to `which said base is movable connected with the circuit conductor system and movable in the same direction ot and lateral to said contact tace, detachably engaging end wiping upon said contact tace ot said terminal.

il). rlhe combination with a switch unit comprising a base and switching mechanism carried therelfyv on one side thereot, et eupplemcntfil terminal structure on the opposite Side ot said baee and connected with Said switching inechanism and comprising a terminal having a contact 'tace Substantially parallel with the rear tace oit said base, and terminal. structure With respect to Vwhich said base :ie movable connected with the circuit conductor system and movable in the Same direction of and lateral to said. contact tace coinprieng a lvielding Contact abuttin against and 'wiping 'upon said con tact tace olf said terminnl,

li. The con'ibination with relatively :lined termimil etructiu'e connected with the circ-uit conductor system, ot a detachable basic pivotallv movable with respect to seid terminal structure, switching mechanism carried by Said base, a houeing `for said switching mechanism pivotally movable with respect to both said structure and said base, supplen'iental terminal structure carried by said base connected with said switching mechanism and adapted to engage said tiret-named terminal structure, spring means opposing movement ot said base atter engegement ot seid terminal structures with each other, and ineens lor cetzichably holding Said terminal structures in engagement with each other in opposition to said spring means.

12. The combination with relatively lined terminal stri'ietin'e connecteifl with the circuit conductor System, ot a base movable with rcepect to said terminal structure, switching mechanism carried by Said base, einmlemontal terminal structure carried by Said basse connected with said switching ineclninisni and adapted to engage said irstw named terminal structure, spring means opposing niiovement ot Said base after engagement ot said terminal structures with each other, a` housing enclosing said switching mechanism and movable with respect to said base and engaging said base, and means holding said housing in predeterniiined position with reeoect to Said tirst-nen'ied terminal etriiicture and thereby holding said terminal structures in engagement Vwith each other in opposition to said Spring means.

13. `'lhe combination with a housing(` ot terminal structure therein connected with the circuit conductor system.) a base carried by and detachable and movable with respect lill carried thereby. oit suiiplemental terminal structure carried by said base and connected with said sivitchine` mechanism2 terminal structure connected with the circuit conductor system, a contact electricall?,Y connected w ith one ot said terminal structures and en- ".nej another oit said terminal. struc ires, yable support2 and a pivot. pin cu-:ried by said support, said contact having` a slot receivingv said pin, said slot havinggj' a deiith 1uatcriallvT ri-cater than the diameter oif said p'iin whereby said contact is sel'li-iligning1 in its engagfge-.ment with said other oit said terminal structures.

2l. The comoinatien with a switch unit comprisin5.;l a base and switching mechanism carried thereby.. ot supplemental. terminal structure carried by said base and connected with said switchinev i'nechanism, terminal structure connected with the circuit conductor system, a Contact electricalli,T connected with one oil .said terminal strnetiu'es and en; 'aingi` another ot said terminal. structures, a movable support, a pivot pin carried by said supper@ said contact having a slot receiving' said pin. said slot having a depth materially Agreater than the diameter oit said pin, vf'hereby said contact is seltali.'ning in its engagement With said other ot said terminal structures, and a pivot tor supporting; said base and whose airis is par# allel With the anis ot said iirst named pivot.

Q2. The combination with a switch unit comprising; a base and switching` mechanism carried thereby` oit supplemental terniinal structure carried by said base and connected with said switching; mechanism, terminal structure connected. with the circuit conductor system,` contact electrically connected with one ot said terminal structures and abuttinn' against another ot said terminal struct'ures9 :rniifivable support, said contact pivoted to sait sulniort9 and a spring' exertinn' av 'force upon said contactsuliistal'ltiallv at its pivotal axis and forcing); said contact toward said other ot said tern'linal structures, whereby said contact aligns itsel'iE with .respect to said other et said tern'rinal structures and presses thcreagainst.

25E. The combination with a switch unit comprising; a base and switching mechanism carried thereby, olf supplemental terminal structure carried by said base and connected with said switching meel anisim terminal structure connected with the circuit conductor system., a contact electrically connected with one oil said terniinal structures and abutting aggainsist another ot' said terminal strucn tures, a movable support, said contact pivoted to said support, a spring exerting1 a 'torce upon said Contact substantially at its pivotal axis and 'forcing said contact toward said other of said terminal strnctnrem whereby said contact aligns itselt with respect to said other et said terminal strne tures and presses thereagainst, and a pivot tol' supporting said base and having its airis substantially parallel with said pivotal anis ot said contact.

2li. The combination with a support, ot a base pivoted thereon, sai/"itching;` mechanism carried by said base, means enacting` with said hase and .support tor guiding' said base in its pivotal movementwith respect to said support, a housing member pivoted co-afcially with said base 'for movement With respect to said suifiport and said. base and. tor engaging said base, and. means coactinsg` with said support and said member :lor holding,` said member and base to said support.

25. The combination with a housing, ot a pivoted. base movable with respect there-A to, sivitelling` mechanism carried bv said base, means co-acting with said housing' and said base iter guiding1 said base to predetermined position ivith respect to said housinc;` circuit conductors extending; into said heus@ me and connecting with said switching' nechanisrm a see "id housing' enclosinn' sail! switching' .mechanism and moif'able 1with respect to said hase and said tiret named housing, and means on said second named hou ing adapted to engage said base tor holdino' it to said tirst named housing'. i

'26. The combination with a housing', o t a pivotedbase movable with respect thereto. ,switching mechanism carried liv said base', n'ieans co-aetinggv -with said housing` and saidv base .'l'or guiding said base to predetermined position with respectto said housing, circuit conductors extending' into said housing and cennecting` with said switcliing` mecha@ nism', a second housing enclosing; said switching mechanism and movable ivith respect to said basl and said tirst named heus* ingr, means on said second named heusinu; adapted to engage said base Yfor lioi'linn' it to said lirst named housing,y and nwansmco acting?)y with said housings :tor holding' said base and said second named luntsinn, in pre-- determined. position with respect i to said lirst named honsine. i

2i'. 'lhe combination. with a housing', et a pivoted b se movable with 'respect thereto? switching mechanismV carried b v said base7 means cti-acting with said housing@` and. said base tor guiding said base to predetermined position with respect to said hoiiisinp; circuit conductors extending into said housine' and connecting With said switching; ificchanisnn a second hoi sing' enclosing said swit'hinej mechanism pivoted co-aiially with said base and movable with respect to said base and said lirst named housing, and means on. said second named hermine; adapted to engage said base for holding' it to said first named housing'. i

28. rllhe combination with a lioiuiine'7 ot a pivoted base movable with respect thereto, switching mechanism carried by said base7 Sill Vand said first named housing, means on said second named housing adapted to engage said base for holding it to said ijirst named housing, and means eo-act-ingr with said housings tor hold-ing said base and said second named housing` in predetern'iined position with respect to said irst named housinO.

,b 29. The combination `with a housing, ot a pivoted base movable with respect thereto, switching mechanism carried by said base, means co-actmg with said housing and said base for guiding said base to vpredetern'iined'position with respect to said housing.y

Vcircuit conductors extending into said housing and connecting with said suit-ching mechanism, av second housingl enclosing said switching mechanism and movable with respect to said base and said .first named housing, means on said second named housing adapted to engage saidbase for holding it to said iirst named housing,'and toggle inechanism eo-acting with said housings for holdingsaid base and said second nanled heus* ing in predetermined position with respect to said lirst named housing'.

80.*The' combination with a housing, of a pivoted base movable with respect thereto, switching mechanism carried by said base, means'coLacting .with said housing and said base tor guiding said` base to predetermined position with respect to said housing, circuit conductors extending' into said housing and connecting with said switching mechanism, a second housing enclosing said switching mechanism pivoted ctr-axially with said base and movable with respect to said base `and said l'irst named housing,'means on said secnew/,eee

ond named housing adapted to engage lsaid base for holding it to said lirst named housing, and toggle mechanism co-acling with said housings for holding said base and said second named housing in predetermined position with respect to said first named housing.

The combination with a permanent wiring system con'iprising circuit comluctors and permanently tixed terminal structures to which said conductors are connected, and a housing' enclosing said terminal structures, ot a hase detachably supported with respect to said housing and termina-l structures, a switch carried by said base, supplemental switch terminals carried by said base on the side opposite to said switching` mechanism and detachahlyv engaging said terminal structures, a second housing movable independently ot said base and said first named housing, and means co-acting with said .housings for holding said base and said second named housing in predetermined position with respect to said iirst named housing.

The combination with a pernnment wiring system comprising circuit conductors and permanently iixed terminal structures to which-said conductors are connected, and a housing enclosing said terminal structures", of a base detachably supported with respect to said housing and teri'uinal structures, a switch carried by said hase, supplemental switch terminals carried by said hase on the side opposite to said switching mechanism and detachably engaging said terminnal structures, a second housingl movable independently ofsaid base and said lirst named housing, mechanism carried b v said housing in detached relation to said switching mechanism for actuating said switching niechanism, and means cosacting with said housings for holding said base and said seeond :named housing in predeternlined posi-- tion with respect to said first nanied housing.

VILTA M lli. SCOTT.

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